There are a number of aspects you need to consider when thinking about planning a project of this magnitude.
1. You need to determine what is the competition? What off campus housing already exists, what are their rents, tenants like, etc... get to know everything about who else is renting to students.
2. You need to contact the college and find out if they would be willing to partner with you on solving the housing problem. The college I attended did a similar project and hired out the development of almost 400 units to a known and respected developer from the area (this could be a critical component... he was known and very well established). If they seem open to it that would be the best way to proceed as they can help you in all sorts of ways you never thought about.
3. You will need some serious Cash to do this and have staying power. The one down fall about student housing is that while you are booming and raking in cash during School what happens when Summer comes and the majority goes home? You suddenly have a severe shortage in prospective tenants. (keep in mind that many students will not want to rent yearly because they are home for 2-3 months every summer, and in some cases a month or more during christmas/new years).
Those are just some quick things that I can think of off the top of my head... There is however some amazing potential in the student housing market.... I know you are in the NY area as am I, I would interested to know where your prospective area would be and possibly help you out :) Feel free to message me...